Fifty years ago this week, a portly gentleman stood up in the Senate House of Cambridge University and launched a meme - an infectious idea - which has reverberated ever since. The speaker was a successful novelist who had earlier in life been a promising scientist before his career was blighted by an unfortunate experimental mistake. (He and a colleague thought they had found a way to make vitamin A, but it turned out that they hadn't.) During the war he had discovered a talent for scientific administration and in the postwar era had become a knight and a pillar of the establishment. His name was Charles Percy (CP) Snow.

Snow's Big Idea was that there were "two cultures" in our society - that of the "literary intellectuals" (as he called them) and that of the natural scientists. His argument was that there existed a profound division - characterised by mutual incomprehension and distrust - between the two cultures, and that this division had disastrous consequences for society.

The defining characteristic of a successful Big Idea is that it should be big enough to suggest profundity, but not so big as to be difficult to comprehend. In that respect, the only serious competitor to the Two Cultures meme over the past half-century has been Thomas Kuhn's notion of "paradigm shift". Both ideas are endlessly parroted, frequently misinterpreted and relentlessly deployed to lend a touch of academic class to intellectual brawls that might otherwise look vulgar.

Over the years, Snow's meme has been subjected to criticism and abuse, but the idea of mutually uncomprehending cultures still seems relevant to understanding why important segments of our society are struggling to come to terms with a networked world. In our case, the gap is not between the humanities and the sciences but those who are obsessed with lock-down and control, on the one hand, and those who celebrate openness and unfettered creativity on the other. The odd thing is that one finds arts and scientific types on both sides of this divide.

The legal scholar James Boyle describes this as the division between those who are culturally agoraphobic and those who are not. In a couple of recent lectures (available online at http://bit.ly/tYEFj and http://bit.ly/1KVUr4) he has suggested two intriguing thought experiments to illustrate the gap.

Imagine, he says, you're back in the early 1990s. The potential of electronic networking is dawning on the world, and there are two possible paths of development. The first is a version of the French Minitel system - government-provided terminals in every home on which appear information and services from a small number of approved providers (the BBC and Guardian for news, the Met Office for weather information, Reuters for stockmarket information, and so on). Everything is controlled and reliable. The other option is a publishing system in which anybody can publish anything - including lies, propaganda and pornography - with no prior approval. Question: which system would you have chosen?

In Boyle's second experiment, the task is to design the world's first global encyclopedia. One proposal is for a huge enterprise that starts by appointing an editorial board of the world's foremost thinkers. It recruits a staff of experienced commissioning editors who solicit articles from respected authorities. The resulting submissions are rigorously checked for factual accuracy and impartiality before being published. The publication is updated once every five years. The alternative proposal is from a guy who says "Well, I think we should put up a website and ask people to write stuff for it." Which one would you have chosen?

Boyle's point is that most of us would have chosen the Minitel and Britannica models and thus denied the world the web and Wikipedia. The cultural agoraphobia from which most of us suffer leads us always to overemphasise the downsides of openness and lack of central control, and to overvalue the virtues of order and authority. And that is what is rendering us incapable of harnessing the potential benefits of networked technology. Industries and governments are wasting incalculable amounts of money and energy in Canute-like resistance to the oncoming wave when what they should be doing is figuring out ways to ride it.

Which brings us back to dear old Snow. In 1959 he argued that the gap between his "two cultures" was holding us back from applying technology to solve the problems of the world. Fifty years on, we're still in the same boat. The cultures have changed, but the problem remains.